Purpose: This research examined the factors affecting several types of student engagement, namely agentic, behavioral, emotional and cognitive engagement. Specifically, it examined the effect of e-learning system usability on student engagement and explored teacher behavior's possible intervening impact on this relationship. Design/methodology/approach: Data were collected from 418 students studying at different specializations at Omani private academic institutions. This study employed a quantitative methodology and utilized the Smart-PLS for data analyses. Findings: The findings showed that e-learning system usability influenced significantly and positively agentic, behavioral and cognitive engagement. However, the link between e-learning system usability and emotional engagement was not significant. Moreover, teacher behavior mediated the relationship between e-learning system usability and the four types of engagement. Originality/value: This study improves one's understanding of how the interaction of e-learning system usability and teacher behavior affects several aspects of student engagement. It also helps higher education administrators and policymakers by exploring the influential effects of e-learning systems usability and teacher behavior on facilitating students' engagement.